The present invention relates to an apparatus for assisting limb and a computer program for executing a computer for the apparatus.
Walk-assisting devices which are designed to provide an assist force required for a user in walking have been disclosed in recent years. A walk-assisting device is typically used by a person who has difficulty in walking by himself, such as one lost muscle strength or suffering from leg injury. In addition, it is anticipated that a walk-assisting device will be applied to exercise and amusement, aiming at improvement in muscle strength and walking posture.
A patent document 1 discloses a walk-assisting device which is attached to a lower limb of a user and has joint actuators (actuator: a combination of an electric motor and reduction gears), which are placed coaxially with a hip joint, a knee joint and an ankle joint of the user, respectively, so as to rotate them, so that the walk-assisting device provides the user with a certain drive force. Patent document 1: Japanese Published Patent Application H05-329186 (paragraphs 0034-0036, FIG. 15 and FIG. 16)
However, the walk-assisting device described in the patent document 1 has a problem that because the device has supporting members which tightly restrict a whole lower limb of a user, there is a great inertial moment resulting from movement of the lower limb. Generally speaking, it is necessary that a walk-assisting device should drive supporting members synchronously with movement of a lower limb of a user. If a great inertial moment occurs, it may be possibly difficult to carry out synchronous control due to response delay of the supporting members.
If an actuator having sufficient capacity is adopted for a joint driving unit so as to cancel an adverse effect due to a great inertial moment, the joint driving unit results in a large-size one, which consumes a great amount of power.
In addition, a great inertial moment leads to degraded feeling and fatigue of a user wearing a walk-assisting device.
The walk-assisting device described in the patent document 1, in which a whole lower limb of a user is tightly restricted by support members and the user needs to support total weight including his self weight and the walk-assisting device, he tends to experience uncomfortably restrictive feeling, pain and feeling of a high load
Because the walk-assisting device restricts a whole lower limb with support members, it is necessary that the support members should be a custom-built model so that the device is compatible with his figure and habit in walking.